Extramedullary myeloid tumors in primary myelofibrosis

Abstract

T sclerosis in association with myeloid metaplasia has emerged as a definite clinical and pathological entity during the last several decades. While this syndrome has been designated by a variety of terms, it is generally acknowledged to consist of (1) splenomegaly, and often hepatomegaly; (2) the presence of immature white and red blood cells in the peripheral blood, usually with anemia and often with circulating megakaryocytes (leucoerythroblastic blood picture); (3) myeloid metaplasia involving the spleen and liver in particular; (4) myelofibrosis at some time during the course of the disease; (5) normal or elevated leukocyte alkaline phosphatase determinations; (6) absence of specific chromosomal abnormalities; and (7) an irreversible and usually slowly progressive course, terminating in death from intercurrent infection, hemorrhage, cardiovascular complications, blastic crisis or frank exhaustion. The clinical and pathological features of this syndrome and the controversial views in regard to its pathogenesis have been the subject of numerous reviews. Among the most recent are those of Rohr, Andreasen,2 Bowdler and Prankerd,4 Pitcock et al.,23 Bouroncle and Doan3 and Dameshek and Gunz.13 We have been impressed recently with the large masses of extramedullary myeloid tissue which one occasionally encounters in this entity. So impressive may these tumors become that they may trap the unwary clinician or pathologist into thinking that he is dealing with a soft part sarcoma or carcinoma. There is a paucity of documentation of such cases despite general acceptance of their existence.